Abstract

Midgap state-based -junctions have been fabricated by a focused ion-beam system using 45° symmetric [001] tilt bicrystal substrates. Measurements, performed by inserting the junctions in a superconducting loop (as a double-phase sensitive test), show both an unconventional nonmonotonic temperature dependence of the Josephson current, with a local minimum at a crossover temperature and, around , a half flux quantum shift in the critical current versus magnetic field modulations, clear signs of a crossover with temperature. Such results demonstrate that conventional 45° symmetric grain boundary junctions may have potential for applications, from digital circuits to quantum computing.